Justin Bieber Vomits On Stage in Arizona; Tweets 'Milk Was a Bad Choice' (Video)

The pop star was in the middle of a dance number at the opening concert of his Believe tour when he suddenly turned around and threw up on stage.

Everyone has embarrassing moments, but we don't all have them in front of a concert arena full of people (and now, thanks to YouTube, the whole world).

Justin Bieber premiered his Believe tour as scheduled last night in Glendale, Arizona, but the show was not perfect. Unfortunately, the 18-year-old Canadian superstar was feeling a bit under the weather, giving a new meaning to Bieber Fever -- and in a show-must-go-on manner, Bieber threw up on stage not once, but twice during the concert.

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The first was the most visual (for those with stomachs as weak as Bieber's, please ignore the video clip below). Halfway through the concert, during a dance performance of "Out of Town Girl," Bieber suddenly turned around and doubled over while his dancers continued to dance and his backing track continued to play. Fans watched on as their beloved Biebs got sick all over the stage floor before running off backstage. The dancers continued through the song, and a DJ took over momentarily while some unfortunate person cleaned up the mess.

Bieber returned to the shrieking delight of his fans, apologizing, "I'm sorry, I'm going to slow things down." He then segued into an acoustic song, "Fall," and being the trooper he is -- got on a platform on a mobile crane and soared above the crowd.

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But a few songs later, Bieber was sick again. At the beginning of "Beauty and a Beat," a duet he was singing with Nicki Minaj via a pre-recorded video for the performance, Bieber ran off stage again.

When he returned a few minutes later, the singer explained to his concerned fans, "It's hard for me, you know, not feeling great and throwing up in front of a bunch of people," he said. The crowd, no doubt, will support Bieber through anything. "Will you love me even though I'm throwing up on stage?" If the shrieks that followed were any indication, the answer is a resounding, "Yes!"

Bieber has more than 70 shows to go on the international tour over the next few months, so he's taking any moment he can get to rest up and recover. The singer tweeted a picture of himself in bed late last night to his more than 28 million followers, saying he was "getting better for tomorrow's show." Of course, only Justin can fully explain why he threw up in the first place... but an Anchorman quote is all he had to say: